1. Field of the Invention
The present invention relates to a substrate processing apparatus for processing a substrate, a substrate processing method or a semiconductor device manufacturing method performed using the substrate processing apparatus, and a non-transitory computer-readable recording medium having recorded thereon a substrate processing program, and more particularly, to a semiconductor device manufacturing method capable of reducing the amount of pollution of a substrate such as a semiconductor wafer (hereinafter referred to simply as a ‘wafer’) when the substrate is processed by, for example, plasma, a substrate processing apparatus and a non-transitory computer-readable recording medium.
2. Description of the Related Art
For example, in order to improve the reliability of a tunneling insulating film of a flash memory, a silicon oxynitride (SiON) film (hereinafter referred to as an “oxynitride film”) is used instead of a silicon oxide (SiO) film (hereinafter referred to as an “oxide film”) employed in the related art. Among methods of forming an oxynitride film, a method of forming an oxide film on a surface of a silicon substrate using N2O gas and introducing nitrogen atoms into an interface between the silicon substrate and the oxide film has been well known. However, as semiconductor devices (devices) are becoming finer, an oxynitride film according to the related art does not satisfy demands for film quality. Thus, a technique of introducing nitrogen atoms into both an interface between the oxynitride film and the silicon substrate and a surface of the oxynitride film by additionally nitridating the surface of the oxynitride film using plasma is used.
Although nitridation performed by plasma is advantageous in terms of selectivity for intensively nitridating a surface of the oxynitride film, low-temperature processing, etc., a substrate may be contaminated by a contaminant (such as heavy metals) contained in components of a process chamber for nitridating the substrate. Although heavy-metal contamination may be decreased by coating the inside of the process chamber with quartz, an alkali metal generated from quartz (particularly, sodium) may cause a serious problem.
Since a back surface of the substrate is in contact with a susceptor on which the substrate is placed in the process chamber, a contaminant may be directly transferred from the susceptor to the substrate and thus the substrate may be easily contaminated. Thus, recently, metal contamination of even a back surface of a substrate has been strictly managed in order to prevent cross-contamination from occurring between substrate processing apparatuses.
For example, in order to decrease an amount of metal contamination, for example, when a device is moved upward, a technique of performing plasma-discharging while supplying nitrogen gas into the process chamber and performing plasma-discharging while supplying oxygen gas into the process chamber in a state in which a product wafer is not placed on the susceptor installed in the process chamber may be used. Also, in order to decrease an amount of metal contamination, for example, when a device is moved upward, a technique of performing plasma-discharging to a higher plasma discharging power level while supplying nitrogen gas into the process chamber prior to a production treatment in a state in which a product wafer is not placed on the susceptor installed in the process chamber than a plasma discharging power level after the production treatment may be used. Also, in order to decrease an amount of metal contamination, a technique of forming a susceptor of a non-metal material such as quartz may be used. However, when these techniques are used, a product substrate cannot be suppressed from or cannot always be sufficiently suppressed from being contaminated from, for example, a contaminant generated from quartz in the process chamber.